Printing telegraph private branch exchange system



F. S. KINKEAD April 2, 1935.

PRINTING TELEGRAPH PRIVATE BRANCH EXCHANGE SYSTEM Filed Dec. 2l, 1933 4 Sheets-Sheet 1 /NVE/vrof? f'. 5. K/NKEAD F. S. KINKEAD April 2, 1935.

PRINTING TELEGRAPH PRIVATE BRANCH EXCHANGE SYSTEM Filed Dec. 21, 1933 4-Sheets-Sheet 2 ATTORNEY 4 Sheets-Sheet 5 F. S. KINKEAD Filed Dec.

PRINTING TEL'EGRAPI-I` PRIVATE BRANCH EXCHANGE SYSTEM /NvE/vToR By PS K/N/(EAD April 2, 1935.

MATTO/WEF April F. s. KINKEAD 1,996,516

PRINTING TELEGRAPH PRIVATE BRANCH EXCHANGE SYSTEM Filed Dec. 21, 1933 4 sheets-.sheet 4 u Patented Apr. 2, 1935 UNirsn sra'rssj PATENT oFFicE Y 1,996,516Y f l K l PRINTING TELEGRAPH PnIvATE BRANCH- f EXCHANGEl SYSTEM s Fullerton S. Kinkead, lRidgefield Park, N." JI., as-

signor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a. corporation' ofNew Application patentieren 1933, sleiialNo. 703,419 Y s claims. (crus- 2i This invention. relates to printing telegraph systems andmore particularly to telephone exchange systems wherein automaticallyand ,die rectively operable switches are employed at ,a centraloice for establishing telegraphic connections between two or more subscribers stations.

The invention has for its main object to interrupt anyestablished connection between two subscribers stations ,for the purpose of including either of the interconnected stations in a broadcast circuit.

In the system described herein is a group arrangement of conference, orV broadcastcircuits whereby the subscribers stations maybe arranged in groups and any group selectedforv connection to any subscribers station in another glOllD- Heretofore in private branch exchange Asystems employing conference circuitsthe broadcast group was arranged on a nonseizurey basis and should any station be busyat the time a call is made to it for the purpose of includingit in a broadcast circuit, the subscriber wishing to establish the broadcast circuit would receive a busy signal in the same lmanner as in the establishment of an .individual connection. Upon receipt of the busy signal the subscriber releases his call key so as to restore to normal the equipment at the central cnice which Ywasoperated by a call. A system of-the character just described is disclosed in U. S. Patent 1,958,930, granted to F. J. Singer on May 15,1934.

A feature of the present invention is the provision of'a broadcast group arranged on a seizure basis whereby all stations in any group may be connected for broadcast purposes to a calling subscribers station at any time even though one or more stations in the desired group is engaged in an individual connection thereby interrupting a message that is being transmitted over the individual connection.

Another feature is the provision whereby no Vsubscriber can interrupt an established broadcast circuit designed on a seizure basis for the purpose of establishing an individual connection with one of the stations engagedin the broadcastcircuit. In the preferred form illustrated anddescribed herein, the invention contemplates, like that disclosed in Patent 1,958,930, supra, the provision of a one hundred line machine switching telegraph private branch exchange system employing automatically operated line iinder and hunting connector switches of the step-by-step type However, it is understood, like in Patent 1,958,.- 930, that the number of lines maybeincreased as jthermachine -switching telephone systems,

which are'wellknown in the art by adding one or more selector switches -of the step-by-step type with the necessary rotary single movement switches for handling' call numbers of two or more digits Y y Other objectsand features will be found in the following detailedy description vand accompanying drawings. 'A

Referring :to the drawings: Figure 1 shows twor subscribers stations with ytheir respectively associated equipment at the central-cnice. In the `lower vportion is shown a schematic layout ofthe rnecessary equipment for receiving-and'gsending printer messages at a subupper iportion Iis shown an; oblong; representing theequipment at a second subscribers station,

lsay station C; the equipment at station C being intendedto be identical with-that of station A. SationsC-:and A are shown connected for establishingga call'tov and receiving a call from Yany other subscribers station. The central of'ce equipment.associatedwitn station A is shown connected as one 'branch' of abroadcast group.

. Fig; 2, shows, :in Voblongs, line nder switches, a huntinggconnector. switch and the associated miscellaneous -Y alarm circuits. These figures shown inpblongs; are intended to be identical with; the iigures-of corresponding numbers disclosed in Patent 1,958,93v0fsupra.` n Y Fig. 3 shows in schematic layout, the necessary equipment for. receiving andsending'printer mes- .sagesat Vanother subscribers station, say station Bincluding'a transmitting and -receiving printer with associated'driving vmotor and control circuit therefor. ,-Also shown in this figure is equip- "operationpf the broadcast circuit cast' purposes, the subscriber at station C operates call key such as key at station A, and the call is automatically established through the line finder, to the hunting connector switch both shown in Fig. 2 in a manner described in Patent 1,958,930, supra, for establishingv the individual connection to station B. .When the hunting connector switch is seized and the subscriber receives the signal, such as the extinguishing of lamp, for example, lamp IIS at station A, indicating that the system is prepared to receive the dialing impulses, a dial such as dialy |04 'at station is operated to send the broadcast code number of the desired group. A groundedcon'- ductor is immediately connected thecircuit extending over the sleeve circuit conductor 451, through the winding of start relay 52| to grounded battery. Relay 52|, in operating, closes (1) at its upper armature and contact an obviousop- @rating circuit extending in parallel paths through the windings, in parallel, of the cutthrough relays 5H to 520 to grounded battery, and (2) at its lower armature a circuit extending from grounded battery, lower armature and front'contactof relay 52 I, conductor-53|, makebefore-break contacts of relay 523, through the winding of relay 524 to ground.l Relays'5ll to 520 operate and thereby cut through the tip and the ring conductors extending from each of the stations in the d esired group to grounded positive battery 532 'and Agrounded negative battery 533, respectively. The grounded'negativebattery 533 is now connected in a circuit extending to ground at thev armature and back Contact of a relay, corresponding 'to'.'relay |02'at station A, at each of the stations in the desired group. At the front contact of the relay, corresponding to relay |02 at station A, thefcircuit extending to the grounded positive battery E32 is opened." The tip conductor |36 and ringfconductor |31 extendling from station Axwhich is included in the desired group, is shown, in detail, connected to the outer upper and inner upper armatures respectively of relay 5H andthe operation of relay 5|| actuate's these V'armatures intoengagement with their respectively associated" front contacts to close a circuit extendingthrough the .batteries 532 and 533. Each of relays5|| to 520, in operating, closes at its lower armature and Contact, a circuit for operating the cut-olf relay of the line extending to one of the stations of the `desired group, the cut-off relay v|38 associated with station A being operatedover the circuit including conductor 534. The ground which operates relay !39 is extended directly to the sleeve multiple of the associated line onthe connector switch over the lead 41|.. The cut-off relays, Vin operating, make the lines extending tothe stations in the. desired group busyv to subsequent calls for individual connections; t

Relay 524operates in response to the operation of relay 52! described above, and closes a circuit extending through the left winding of relay 523 and the winding of relay V522 to grundedbattery. Relay 523 is made slow operating in order to ensure the complete operation of relay 522 before relay 523 operates. `Relays 523 and 522 operate. RelayY 522 in operating, disconnects grounded negative battery 533 and connects in its place grounded positive battery 535 tothe ring conductors extending to the stations in the desired group and this reversalof current operates a polarized relay, corresponding to relay H3 at station A, at each of the desired stations. This reversal, like that describedin the above hunting-connector switch with the contact connect'ed to conductorV 451 causes relays 4|1 and llll` shown in Fig. 4 of Patent 1,958,930, supra, yto operate in a manner hereinbefore described whereby relay 4|1 causes the ltip and ring conductor of the line extending to station A to be connected .through to the hunting connector brushes, and relay 4|0 causes a reversal 'of current on the lin'e extending to station Cto thereby start the motor thereof in a manner described in Patent 1,958,930, supra'. The starting of the motor at station C operates a buzzer corresponding to buzzer` |29 at station A, which serves as a signal that the connection-has been completed and for the subscriber to release the call key corresponding to key |0| at station A. To release the buzzer the operator momentarily operates the'call key to its left hand position, upon the release of the key the subscriberv starts sending Athe message -to the desiredv stations,

which'is transmitted over conductor 465,1throu'gh the rightV windings of relays k525 and 526, in series, and back over the conductorf466. Relays 525 andl'526 respond to the message impulses.

Relay 525 repeats the message impulses over conductors 536 and 531 through thevprinter magnet at each of the stations, preferably five, in the iirst subgroup ofthe stations in the desired group, and relay 523 repeats the same impulses over conductors 538 and 539 to the printer magnet at each of the stations, also preferably five, of the secondsubgroup. The circuit for repeating the message to station A which isincluded in the desired group isftraceable from'grounded positive battery 532 or grounded negative battery 530,'cond`uctor536, front contact and outer upper armature of relay 5| l, conductor |36, through the equipment at station A, back over conductor |31, inner upper armature and front contact of relay 5H, conductor 531, armaturev and back contact of relay 522 to grounded negative battery 533. The release of the equipment in the broadcast circuit is eiected by transmitting a stop signal from the calling station only in a manner described in Patent 1,958,930,

supra.

Seizure of subscribers station If station A is in operation and in communication with Vanother station by an individual connection and a connectionv is established to the broadcast group of which station A is a member, station A is taken from the individual connection.Vv In such an event the line nder and hunting connection switches by which the individual connection was established `are returned to normal.

Assumethat station A has established an individual connection with Ystation B and that station C has established connection to the broadcast group of which station `A is a member. After connection is established to conductors 451, 465 and 465 the action of relays described above.

52|, 522, 523 and 521|` is identical with that Relays 5H to 529 operate to connect conductors |36 and |31 and corresponding conductors of other station circuits comprising thebroadcast group in parallel to conducf tors 535 and 531respectively.' The momentary reversal of poiarityrapplied to thek conductors corresponding to |31 through conductors-531and 539 during the tirnerelay 522-is operated causes all idle stations 'of the group to be startedas described above. At all stations'of thegroup pre viously started as the result ofthe establishment of individual connections, as is the'case of station A, the momentary reversal-of polarityfapplied to conductor |31 and corresponding conductors, performs anotheriunction. During the time reiay 5221is operatedno current will flowin .the upper winding orY relay |21 of Fig. 1 since vboth sides ofits operating path are terminated in positive grounded battery. 'I'his path may be traced from positive grounded battery, makecontact of relay 522, conductor 531, upper inner armature and make contact of relay` 5H conductor I3?, through the winding of relay |3 of Fig. l, contacts |33 of key 10|, make contact of relay |92, transmitting contacts yof the printer |35, break key contacts |35 through the upper winding of relay |21, conductor |35, upper outer armature and make contacts' of relay y5H "of Fig. 5, conductor 536, lback contact of relay `525 to positive grounded battery. Since no current is Vflowing in the upper winding of relay |21 its armature will be operated away from its lower Contact under the inuence of the current owing through thellower winding; The path of this current is from grounded direct current source, upper armature and contact fof relay |29, conductor |24, and lower winding ofrelay 921 to ground.` Receiving printer magnet |3| therefore releases during the period relay 522 is operated. The momentary opening of thereceivmagnet 3| is recognized by the 'subscriber at station A as a break signal. If the subscriber at station A is at the time transmitting,the break is an indication to stop transmitting. 1

After relay '522 has released, all subscribers stations of the group will be in proper condition for 'reception of the broadcast signals.

Upon operation'ot relay 5|| conductor |40 from the line nder switch Fig. 2 is opened at `the upper outer armature and back contact cf relay 5H and conductor HH is grounded at the upper inner back Contact of relay 5| and its associated' auxiliary contact.v With conductor` |40 open and conductor 14| grounded a release condition is placed upon the lineiinder and hunting connector switches by which lthe individual connection between stations A and B was originally established; 'The release of the line nder and hunting connector switches is described indetail in Patent 1,958,930, supra. The release of the hunting connector-removes ground from conductor S31 and `causes relay SM'of Fig. 3 to' 're lease. The release of relay 66| 'opens permanently at its upper outer and upper middle armatures and associated make contacts conductors 558 and 652 respectively thus causing relay SIU 'to operatev away from its back contactto release receiving'printer magnet 613. A permanent open condition of the magnet 6|3 will indicate to the subscriber at station B that the individually established connection with station A has been interrupted. The operationV of the emergency stop key 561 opens the locking path `of relay 685 by interrupting the path 'from grounded power source, winding, and ylower armature `and make contact of.ire1ay, 606,y key 6&1 and motor control contactsy to fground., The4 release of relay 6|i| will ope'nf at' its upper armature and contactV the `path-from local grounded power source to the printerdriving motor 1569.

Assumel that stationBhas established an individual connection with stationA and that station` C hasiestablished ia-connection with the broadcasting group of which stationV A is-a inember. When the non-locking key 504 of Fig. 3 is operated to the left, lrelay |523Y operates tol cause relay 6|4 to operate.v Relayv5|4 closes ground to conductor 622 to theline finder start lead. The

line finder brushesiclosing ground to conductor 62| causes relay 60| to operate, releasing'relays 623 and 6M. Connection from station B tothe line finder and hunting Yconnector switches .is established' over conductorsc I8 and` 552. Confrnection to station'Afrom .they hunting connector nector switch brushes' close on.` conductors 45?,

l65-and 466 relays52l,` 522,523: and 52d` operate as described above tostart idlel stations of the kbroadcasting group fand. 'cause -break signals to stations previously startedfas` a result of individually 'established connections. The.v operation of relay 5| opens a path through conductor |40; 'upper outer armature 1 and vrmake contact of relay |38 of'Fig. l and conductor 413 to the hunt- 'ing connector causinga permanent-open condition' to be indicated-at stationB; The subscriber Vat' station B, being notified by this open indication thatfstation A haslbe'en seized for broadcast purposes, operatesthe 'emergency stop key 681. The Voperation of keyr|||1Y relea-sesrelayv 505 which in turn releasesfrela'y 605;*With relay 695 released Vther ,linepatlifromtheline iinder through conductor 6|8, upper winding of rrelay'tl, sending printer contacts andbreakfkey 6| 1 is opened and. the path through conductor 602-, winding of relay Theseconditions existingon conductors 652 and Switches .t0 releasej- Y f E 8 causethe line finder iand Ahunting connector Y inthe appendedciaimsjwhere the word circuit orequivalen't language'isused in refer'- ence to the rcofnrnunic':ationvpath between a sub'- equipment such wordsor language are used in the inclusive sense of 'ordinary conductive lines as welles radio'links, carrierlinks'land long telegraph lines including repeaters.VVV

What is claimed is: f y f 1. A printing telegraph exchangesystem cornprising a pluralityof subscribers stations of which a plurality constitutefa group, an impulse sending device atfeach'f said subscribers stations'ior selecting anyone l of said subscribers 'stations' individually for communication' therewith or said 'group of said' subscribersz stations collectively,

scribensfstationl and*the*'autorisatie switching switching apparatus common to said stations and Y controllabley from s'aididevices,y aline interconnecting said apparatus andl each of said subscribers stations, means at each of said subscribers stations for preparing the line for the transmission of impulses -from said impulse sending devicea broadcasting circuit included in said apparatus for said group of said subscribers stations, switching equipment'included in said apparat-us arranged to be operatively connected to a callingY subscribers station by the joint'operation of saidpreparing means and-said impulse sendingV device at the calling k,subscribers station, characterized in this that the switching equipment in response to current impulses received from the impulse sending device at oneofesaid subscribers stations, is arranged Yto connect the line of the calling subscribers station .to the -broadcasting circuit whereby connection for communication purposes is established between the calling subscribers station and all the subscribers stations included in the group at any time even though one or more stations in said selectedgroup are engaged at the time in established individual connections with any other subscribersvstations of the system. 1 f. v

2. A printing telegraph Aexchange system comprising a plurality of t subscribers stations arranged in groups, a printer and driving means therefor at each ofv saidstations, a main station,

switching equipment anda source of current at said main station, a broadcasting circuit at said main station, means in said broadcasting circuit for automatically interconnecting at any time a group of subscribers stations with any one of the other of said subscribers stations, and means responsive to theA establishment of said connection for transmitting a reversalv of current to each of the subscribers stations engaged in said connection whereby the printer at eachy of saidl subscribers stations engaged in the connectionis conditioned for operation. v

3. A printing telegraph exchange system comprising a plurality ofsubscribers `stations arranged in groups, a printer and driving means therefor at each of s aid subscribers stations,a y

main station, a normally'openline circuit connecting each of said subscribers vstations to said main station, a broadcast circuit at said main station for each of said groups .of subscribers stations, a selective switching mechanism atsaid main station whereat theindividuahlinecircuits and the broadcast circuits of said subscribers stations are terminated, circuitclosing means at each of said subscribers stations for conditioning for operation saidv switching mechanism, .an impulse sending device at each of said subscribers stations for sending thecodevsignal ofanydesired subscribers station or desired broadcast circuit to operate saidvswitching mechanism to the terminal to which the desired line circuit or broadcast circuit is connected, a sourceof current at said main circuit, meanrsat said main, station for transmitting, in response to the establishmentfof a connection between a calling subscribers station and a called subscribers stationona group of called subscribers stations throughone of said broadcast circuits, a reversal of; currentfrom said source to each of thesubscribers stations engaged in said connection whereby the driving means for the printers at saidinterconnected subscribers stations are set in operation, means at each of said broadcast circuits operableY when said broadcast vcircuit is selected by said switching mechanism to seize for connection in said broadcastcircuit the printer at a subscribers station whose line `circuit is included in the selectedV broadcast group and is connected in a previously established individual connection with another of said subscribers stations and to disable the printer at said other subscribers station.

4; In-a telegraph exchange system, a plurality of subscribers stations, certain of said stations being arranged in groups, a main station, printing telegraph equipment-and a source of power therefor at 1 each of said subscribers stations, said source being normally disconnected from its associated equipment, a-normally opened line circuit connecting each of said subscribers stations, to said main station, switching means at each of said subscribers stations for closing its associated line circuit, pulsing means at each of said subscribers stations fortransmitting an intermittent current over its associated line circuit, automatically operatedmeans at said main station, sets of contacts in saidautomatically operated means respectivelyarranged to terminate the said line circuitsA extending to said subscribers stations whereby an individual connection to each of the subscribersstations,rmay be established, other sets ofcontacts in said automatically operative means respectively arranged to terminate line ycircuits extending to groups of said subscribers stations, whereby group connections may be established for broadcasting purposes, said automatically operated means being responsive rst to said switching means and then to said pulsing means for interconnecting one of said subscribers stations sets of contacts, means responsive to said automatically operative means for operatively .connecting the power source of each of said subscribers stations Voperatively interconnected Y through its associated printing equipment, and

means at said main station responsive to the pulsing means'of any one of said subscribers stations Vfor automatically,disconnecting one of the group ,stations. line circuit-'engaged in an vindividualv connection overanother set of said contacts at:which the line circuit of the station in each group terminates.

5. In aprinting Vtelegraph exchange system comprising a plurality of subscribers stations, a connection initiating device and an impulse sender at each of said stations, vprinting telegraph transmitting and receiving mechanisms and -a source of driving power therefor at each of said stations, Aa main station, a lsource of current at said main station for operating said mechanism, a normally deenergized circuitconnecting each of said subscribers stations with said main station, a calling; line finder switch at said main station responsive to any one of said connections, initiating devicesa called line hunting connector switch atsaid mainV station arranged to select in response to the operation of the impulse sender at the subscribersv stations whereat vthe connection `initiated device is operated, a terminal in the .hunting connector switchcapable of selection by .group of called subscribers stations for broadcasting purposes. f

6. A printing telegraph exchange system comprising a plurality of subscribers stations, a conlnectioninitiating device and an impulse sender at each of said stations, printing telegraph transmitting and receiving mechanisms and a source of driving'power therefor at each of said stations, a main. station, a source of current at said main station for operating said mechanism, a normally deenergized circuit connecting each of said subscribers' stations with said main station, a calling line iinder switch at said main station responsive to any one of said connection initiating devices, a called line, a hunting connector switch at said main station arranged to select in response to the operation of the impulse sender at the subscribers station whereas the connection initiating device is operated, a terminal in the huntingconnector switch capable of selection by the impulse sender at the calling subscribers station for establishing an individual connection between the calling subscribers station and a called subscribers station, a second terminal in said connector switch capable of selection by the impulse sender at the calling subscribers station for establishing a connection between the calling subscribers station and a group of called subscribers stations, and a broadcast circuit having means for establishing the last mentioned connection at a time when one or more subscribers stations in the desired group are busy in an individual connection with other of said calling subscribers stations.

7. A printing telegraph exchange system cornprising a plurality of subscribers stations, a connection initiating device and an impulse sender at each o said stations, printing telegraph transmitting and receiving mechanisms, and a source of driving power therefor at each of said stations, a main station, a source of current at said main station for operating said mechanism, a normally deenergized circuit connecting each of said subscribers stations with said main station, a calling line iinder switch atrsaid main station responsive to any one of said connection initiating devices, a called line hunting connector switch at said main station arranged to select in response to the operation of the impulse sender at the subscribers station whereat the connection initiating device is operated, a terminal in the hunting connector switch capable of selection by the impulse sender at the calling subscribers station for establishing an individual connection between the calling subscribers station and a called subscribers station, a second terminal in said connector switch capable of selection by the impulse sender at the calling subscribers station for establishing a connection between the calling subscribers station and a group of called subscribers stations, and a broadcast circuit having means for momentarily disabling the mechanism at said subscribers station interconnected in individual connections wherein the subscribers stations of a desired group are included, other means for simultaneously conditioning for operation the mechanisms at all the subscribers stations in the desired group, and still other meansV for causing to be restored to normal the calling line iinder and the called line hunting connector switches previously operated in establishing an individual connection.

f 8. A printing telegraph exchange system comprising a plurality of subscribers stations arranged in groups, a connection initiating device and an impulse sender at each of said stations, printing telegraph transmitting and receiving mechanisms and a source of driving -power therefor in each of said stations, a main station, a calling line nding switch at said main station responsive to any one of said connection initiating devices, a called line hunting connecting switch at said main station arranged to select, in response to the operation of the impulse sender at the subscribers station whereat the connection initiating device is operated, a broadcasting circuit, a terminal in the hunting connecting switch capable of selection by the impulse sender at'the f calling subscribers station for establishing a connection between the calling subscribers station and a group of called subscribers stations through 

